Refrigerant compressor controller



April 23, 1940. s w 2,198,132

REFRIGERANT COMPRESSOR CONTROLLER Filed Oct. 10, 1938 INVENTOR.

PRESSURE ATTORNEYS Patented Apr. 23, 1940 UNITED STATES PATENT OFFICE V 2,198,182 BEFBIGERANT COMPRESSOR CONTROLLER Burton a. Shaw, Bristol, Ina, assignor to Penn Electric Switch 00., Goshen, Ind., a corporation of Iowa Application October 10, 1938, 'Serial No. 234,266

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' pressure at which the refrigerant switch operates.

Another object is to provide a refrigerant compressor controller including a switch for the mo- 10 tor of the refrigerant compressor and a pressure responsive device responding to the pressure in the low side of the refrigerant system, the pressure controller normally causing cut-in and cutout of the switch between predetermined limits, it my present invention contemplating a means to modify the cut-out position only of the pressure controller.

More particularly it is my object to provide in v combination with a movable element which is 20 normally pressure controlled between predetermined cut-in and cut-out limits, av means to change the cut-out pressure only which consists of a second movable element having spring means to urge the first movable element toward 2!! cut-out position, the spring means being effective only during that portion of the movement of the first movable element. which terminates in cut-out of the switch.

Still another object is to provide a modifying 30 means for the operation of a pressure operated pivoted arm of a controller which means consists of a second pivoted arm, a spring urging it to engage the first arm and a stop so positioned with relation to the movement of the first arm 35 that such engagement occurs only during a portion of the travel of the firstarm.

Other objects and advantages of the present invention will be obvious to those skilled in the art by referring to the accompanying specifica- 40 tion and drawing in which a preferred embodiment of the invention is shown and by reference to the appended claims.

In the drawing, Figure 1 is a front elevation of a refrigerant compressor controller embodying my invention showing the cover of the'housing removed and some parts being shown in section, the controller being combined diagrammatically with a refrigerant system and the circuit of the motor thereof.

Figure 2 is a sectional view on the line 2-2 of Figure l. v

Figure 3 is a diagrammatic view of the parts as shown in Figure 1 showing them in a high pressure position.

I (Cl. 02-4) Figure 4 is a similar diagrammatic view show-. ing the parts in an intermediate position.

Figure 5 is a similar diagrammatic view showing the parts in low pressure position and the switch in cut-out position; and 8 Figure 6 is a graphical view showing the operation of my invention.

0n the accompanying drawing I have used the reference numeral III to indicate generally a switch housing. Within the switch housing 10 a bell crank having a lever l2 and a lever I3 is pivoted on a pin i4: The'lever i3 is responsive to the pressure in the low side of a refrigerant system shown diagrammatically in Figure 1.

The refrigerant system comprises a refrigerant compressor RC, a motor M for operating the compressor, a condenser C and an evaporator E. The usual expansion valve V, thermostatically controlled by a bulb 3, is also shown.

The low side of the refrigerant system is in dicated at IS. A line I6 extends therefrom to a pressure responsive device P comprising a bellowshousing i1 and a bellows IS. The bellows .with a nut 2i. Threaded in the nut 2| is an adjusting screw 22 terminating in a knob 23 exterior of the housing Ill.

An extension 24 is connected with the arm l2 of the bell crank and is provided-with a pair of 35 ears 25. The cars 25 carry a pivot pin 26. A. link 21 .is pivoted on the pin 26 and has an extension 28 movable in a slot 28a of a switch arm 29.

The switch arm 2s temiinates in an armature 0 portion 30 adapted to coact with a permanent magnet 3| to secure snap action. of the switch. The armature 30 is attracted by the magnet 3| while a light spring 3i'a tends to swing the armature away from the magnet.

The magnet 3| is mounted on a supporting bar 32 of insulating material which bar also carries a pivot pin 33 supported in a bracket 34. The pin 33 has the switch arm 29 pivoted thereon.

Stationary contacts 35 are provided with which movable contacts 36 are adapted to enact. The

.movable contacts are carried by the armature 30 while stationary contacts are carried by a bracket plate 31. The switch arm 29 and the bracket plate 31 are connected with electric terminals 33 I and 38. These terminals are connected in series with the circuit of the motor M.

The present invention consists particularly in the portion of my apparatus which will now be described. A lever 40 has a pair of side flanges 4| pivoted on the pin H. The lever 40 is adapted to engage the arm l2 of the bell crank as shown in Figure 1. The lever 40 has an upward extension 42 terminating in a right angular portion 43. A spring 44 has its upper end connected with the extension 43 and its lower end connected with a nut 45. An adjusting screw 46 is threaded in the nut 45 and has a shouldered head 41. The head 41 terminates in an operating knob 48.

The shouldered head 4! has a shank 49 which is rotatable in a perforation 50 of the housing l0. Stop pins 5| and 52 are provided to limit the ratation to substantially one revolution.

One of the flanges 4| of the lever 40 has a screw threaded ear 53. A set screw 54 is threaded therein and is adapted to engage the housing Hi to act as a stop for the lever 40 in one of its positions. The stop is adjustable due to the threaded connection 54 with the ear 53 and such adjustment may be retained by a lock nut 55.

Practical operation In the operation of my controller forgetting for the moment the parts 40 to 55 inclusive, a predetermined high pressure against the bellows in the housing ll moves the switch to cut-in position of Figure 3. In Figure 6 the cut-in and cut-out positions are indicated by CI and CO respectively. A line indicated as 32 is the equivalent pressure for a 32 temperature of the evaporator E. It will be noted that the cut-in point is above the line 32 so that in each cycle of operation, the evaporator will attain a temperature sufficiently high to melt the frost therefrom. This is a desirable consideration in the normal operation of the controller. The switch in this position is held closed against the tension of the spring Ella by the magnet 3!.

After the pressure in the housing ll reduces, the link extension 28 will move upwardly in the slot 28a as in Figure and finally strike the top of the slot and then open the switch against the pull of the magnet 3i. As soon as it starts to open, the attraction of the magnet on the armature 3B is reduced so that the spring 31a throws the armature to cut-out position in Figure 5. The controller will accordingly normally operate through its cycles as indicated by the dotted lines in Figure 6, the cycles of operation being relatively short as indicated by X in the winter time and relatively long as indicated by Z in the summer time. This, of course, is due to outside temperature making a longer cycle necessary to pull the pressure in the line l5 down in summer time than in winter time.

With my auxiliary controller illustrated by the parts it] to 55 inclusive the action is modified as indicated by the solid lines representing the cycles in Figure 6. It will be noted that the cutin pressure is still the same, but the cut-out pressures are different. These cut-out pressures are varied at will by adjusting the tension of the spring 44. By increasing the tension in the winter time, the cut-out pressure will be lower and consequently the cycle longer as indicated by Z, when compared to X.

By decreasing the tension of the spring 44, the cut-out pressure will be higher thus shortening the normal summer cycle as indicated at Z.

Accordingly the cycles of operation may be varied as desired without, however, affecting the cut-in pressure at which the switch operates.

To affect the cut-out pressure, but not the cutin pressure, the stop 54 is provided so that it operates as illustrated in Figures 3, 4 and 5. In the high pressure position of Figure 3 the arm l2 has left the arm 40 due to the stop 54 engaging the housing l0 and thereby the tension of the spring 44 is not imposed on the lever [2. After the pressure of the pressure responsive device P recedes, the arm l2 will engage the arm 40 as in Figure 4. Thereafter further recession in the pressure will impose the tension of the spring 44 on the lever 12 after the stop 54 moves away from the housing ID as shown in Figure 5. This imposition of the tension of the spring 44 will continue through the cut-out position and accordingly will cause the cut-out pressure to recede further than would normally be necessary. This is indicated at C0 in Figure 6. The length of the operating cycle is thereby increased as indicated at Z. This adjustment is made for winter operation to lengthen the cycles over the normal length indicated at X.

By reducing the tension of the spring 44 the cut-out pressure in increased (or the degree of recession of the pressure decreased) so that the normal summer cycle may be shortened from Y to Z as illustrated in Figure 6.

Cut-out in this instance occurs at C0". Only two adjustments have been illustrated in Figure 6 as CO and CO, although it is obvious that other cut-out pressures may be secured by the proper positioning of the knob 48. The knob of course, would be graduated in a convenient and Well known manner to indicate to the operator the desired pressure or temperature at which cut-out would occur.

The foregoing described invention makes it possible for a user of a refrigerant system to manually change the cut-out pressure of his automatic controller when desired without in any way affecting the cut-in pressure which remains always above 32 and this insures the desired defrosting of the evaporator coils each cycle of operation.

Various modifications may be made in the disclosed controller without departing from the spirit and scope of the invention and I therefore desire that only such limitations be placed on the appended claims as are necessarily imposed by the prior art.

What I claim and desire to secure by Letters Patent of the United States is:

1. A controller comprising a casing, a pivot pin carried therein, a lever pivoted on said pivot pin, pressure responsive means responding to pressure in the low side of a refrigerant system and cooperating with said pivoted lever to move it in accordance with pressure changes in the refrigerant system, a switch controlled by said pivoted lever and having contacts included in the circuit of the refrigerant compressor motor of said refrigerant system whereby said switch responds normally to predetermined cut-in and cut-out pressures and means to modify the cutout response of said switch comprising a second lever pivoted on said casing, a set screw carried thereby and engageable with said pivot pin, a spring urging said set screw to engage said casing, means for adjusting the tension of said spring, said first lever being engageable with and disengageable from said second lever during oscillation of the first lever between its cut-in and cut-out positions, such engagement occurring while the first lever moves from an intermediate position to cut-out position and such disengagement occurring while said first lever moves from said intermediate position to cut-in position.

2. A controller comprising a casing, a lever pivoted therein, pressure responsive means responding to the pressure of the low side of a refrigerant system and cooperable with said pivoted lever to move it in accordance with pressure changes in the system, a switch controlled by said pivoted lever and connected in the circuit of the refrigerantcompressor motor whereby said switch responds normally to predetermined cutin and cut-out pressures and means to modify the cut-out response of said switch comprising a second lever pivoted in said casing and extending along one wall thereof, a stop carried by said second lever and engageable with said wall, an extension on said second lever extending away from said wall, a spring urging said stop to engage said casing, said first lever being engageable with said second lever during part of the movement of the first lever from its cut-in to its cut-out position and disengageable from the second lever during part of the movement of the first lever from its cut-out to its cut-in position.

3. A refrigerant compressor controller comprising a casing, a pivot pin supported therein, a control lever pivoted on said pin and responding to pressure of the low side of a refrigerant system, a switch controlled thereby, said switch being connected in the circuit of the motor which operates the refrigerant compressor of said system, said control lever being normally swingable between predetermined cut-in and cut-out limits and means to change the cut-out pressure of said control lever comprising a second lever pivoted on said pin, means for stopping said second lever in a predetermined position relative to said casing, spring means urging said second lever to remain in said predetermined position, said control lever as it moves between cut-in and cut-out positions, engaging said second lever and movin said stop means away from said casing whereupon the tension of said spring is imposed on said first lever to modify its cut-out limit.

4. A refrigerant compressor controller comprising a pivoted element responding to pressure of the low side of a refrigerant system, a switch controlled thereby, said switch being connected in the circuit of the motor which operates the refrigerant compressor, said pivoted element being normally operable between predetermined cut-in and cut-out limits and means to change the cut-out limit only of said pivoted element comprising a second element pivoted on the same aziaassaidflrstpivutedelementastopforaaid second pivoted element, spring means urging said second pivoted element to engage said first pivoted element while it moves between an intermediate position and cut-out position, said first pivoted element disengaging said second pivoted element upon engagement of said second pivoted element with said stop while said first pivoted element moves between said intermediate position and cut-in position and means for manually I able between predetermined cut-in and cut-out limits, means to change the effective cut-out pressure to which said movable element responds comprising a second movable element also adjacent said wall of said casing, a stop therefor, an extension on said second movable element and extending away from said wall, spring means connected with said extension and urging said second movable element to engage said stop, said first movable element as it moves between cutmovable element and moving it from engagement with said stop whereupon the tension of said spring is imposed on said first movable element to modify its cut-out limit, and means to adjust the tension of said spring.

in and cut-out positions, engaging said second 6. A refrigerant compressor controller com- I I prising a casing, a lever therein, a bellows respending to pressure of the low side of a refrigerant system, said lever being controlled by said bellows and normally operable between predetermined cut-in and cut-out limits, a switch connected in the circuit of the motor which operates the refrigerant compressor and operatively connected with said lever, and means to change the cut-out limit only of said lever comprising a second lever adjacent one wall of said casing, a stop for said second lever with respect to said wall, resilient means connected with a part of said second lever spaced from said wall, said resilient means urging said second lever to engage said flrst lever while it moves between an intermediate position and cut-out position, saidflrst lever disengaging said second lever by engagement of said second lever with said stop while said first lever moves between said intermediate position and cut-in position, and means for manually changing the tension of said resilient means.

BURTON E. SHAW. 

